Internal handle for multi-mechanism circuit breaker interlocking multiple switch assemblies for simultaneous actuation

ABSTRACT

A molded case circuit breaker having multiple contact operating mechanisms is provided with an internal handle connected directly to the operating members of all of the mechanisms. The central portion of the handle is provided with a stubby bifurcated extension that projects through an opening in the molded housing. A roller freely mounted between the sections of handle extension provides means through which operating forces are transmitted to the handle. The mechanism of the center pole is connected to the handle by means of pins extending from the mechanism into recesses in each portion of the stubby extension, with these recesses extending into close proximity with recesses wherein a bearing pin supporting the force transmitting roller is disposed. The handle also carries spaced insulating barriers disposed on each side of the center pole operating mechanism and inboard of the housing partitions defining the compartment for the center pole. These barriers cooperate with insulating barrier discs floatingly mounted on the transverse tie bar interconnecting the movable contacts of all poles to limit flow of hot gases from the center pole to the outer pole during high current interruption.

United States Patent [1 1 Strobel Oct. 23, 1973 INTERNAL HANDLE FOR MULTI-MECIIANISM CIRCUIT BREAKER INTERLOCKING MULTIPLE SWITCH ASSEMBLIES FOR SIMULTANEOUS ACTUATION [75] Inventor: Albert Strobel, Cherry Hill, NJ.

[73] Assignee: I-T-E Imperial Corporation,

Philadelphia, Pa.

221 Filed: July 27, 1972 21 Appl. No; 275,578

[52] US. Cl 200/50 C, ZOO/DIG. 6, 335/10 [51] Int. Cl. H01h 9/26 [58] Field of Search 20 0/50 C, DIG. 6,

200/172 R,'l72 B; 335/9, 10, 161

[56] References Cited UNITED STATES PATENTS 3,125,653 3/1964 Cole et al. 335/10 1,918,232 7/1933 Baker et al. 335/10 3,069,518 12/1962 5005 200/50 C X 3,272,934 9/1966 Schwartz et al.... 200/50 C 2,067,935 1/1937 Lingal 335/9 Primary Examiner-J. R. Scott Attorney-Sidney G. Faber I I (i [57] ABSTRACT A molded case circuit breaker having multiple contact operating mechanisms is provided with an internal handle connected directly to the operating members of a ll qf the mechanisms. The central portion of the handle extension provides means through which operthat projects through an opening in the molded housing. A roller freely mounted between the sections of handle extension provides means through which operating forces are transmitted to the handle. The mechanism of the center pole is connected to the handle by means of pins extending from the mechanism into recesses in each portion of the stubby extension, with these recesses extending into close proximity with recesses wherein a bearing pin supporting the force transmitting roller is disposed.

The handle also carries spaced insulating barriers disposed on each side of the center pole operating mechanism and inboard of the housing partitions defining the compartment for the center pole. These barriers cooperate with insulating barrier discs floatingly mounted on the transverse tie bar interconnecting the movable contacts of all poles to limit flow of hot gases from the center pole to the outer pole during high current interruption.

12 Claims, 18 Drawing Figures PAIENIEDIICI 23 an SHEET 3 OF 8 SHEET 5 OF 8 PATENIEnum 23 ms INTERNAL HANDLE FOR MULTI-MECHANISM CIRCUIT BREAKER INTERLOCKING MULTIPLE SWITCH ASSEMBLIES FOR SIM ULTANEOUS ACTUATION This invention relates to molded case circuit breakers in general and more particularly relates to circuit breakers of this type having multiple contact operating mechanisms and a novel handle means mechanically interconnecting the multiple mechanisms for simultaneous operation.

In molded case circuit breakers having high current carrying and interrupting capabilities in a compact construction, it is necessary to utilize a plurality of spring powered overcenter toggle contact operating mechanisms. These mechanisms must be tied together by a common handle bar in order to operate simultaneously. This handle bar must be constructed of insulating material in order to isolate the poles from each other and must be strong enough not only to withstand the combined operating forces of all the mechanisms but also must be capable of concentrating all these forces in a small portion of the handle through which operating forces are transmitted to the circuit breaker. Since economical insulating materials have severe strength limitations, the handle bar must be constructed so that within a very limited space, metal components will complement the insulating bar to provide a high strength combination without compromising the insulation requirement.

In accordance with the instant invention, an insulating bar is preferably constructed of glass reinforced alkyd or polyester and is of generally rectangular crosssection. The handle bar is bolted directly to the operating members of the outer pole mechanisms, with the bolt heads being recessed in counterbored holes to conserve space.

The central portion of the handle bar, located over the center pole mechanism, includes a stubby bifurcated protrusion, providing the portion of the handle bar to which operating forces are applied. This portion of the handle bar receives its strength from two shoulder pins that are bolted to the operating member of the center mechanism, with these pins extending into protrusions in each section of the bifurcated extension. Near the free end thereof, the sections of the protrusion are apertured to retain a groove or roll pin, which constitutes the shaft for a cylindrical roller to which external forces are applied.

The shoulder pins reach within close proximity of the roller pin, leaving just enough space therebetween for a solid portion of insulating material. This provides a force-moment arm that is very short, so that the total moment is kept to a minimum at thev weakest area where the metal components at the central region of the handle bar are disposed. This causes loading primarily in sheer rather than in bending, thereby taking advantage of the sheer strength of the insulating material which is considerably higher than its bending strength so that a relatively small cross-section of insulation material is effective.

' During interruption of short-circuit currents, gas pressures within the molded housing are very high, causing distortions in the cover which permits some venting. For the most part, this venting is outward from the outside poles, with relatively high pressure remaining in the center pole, since gases formed therein have very limited escape paths, and in particular do not have 'any substantial benefits from pressures distorting the housing cover. This high pressure in the center pole tends to cause arcing from the center pole to the outer poles.

To maintain isolation between the center pole and outer poles under high current interrupting conditions, the instant invention provides movable barriers that are mounted'directly to the handle bar and cooperate with a pair of floating insulating discs mounted on the tie bar that interconnects the movable contact structures of all phases. High pressure conditions at the center pole force the disc barriers outward against the handle mounted barriers, and these in turn are forced against internal barriers of the housing to substantially block off sidewise escape of ionized gases from the center pole to the outer poles.

Accordingly, a primary object of the instant invention is to provide a novel construction for a handle tie bar connecting together a plurality of circuit breaker contact operating mechanisms.

Another object is to provide a tie bar of this type, with sheet-like insulating barriers disposed on opposite sides of the contact operating mechanism for the center pole.

Still another object is to provide barriers of this type that cooperate with floating sheet-like barriers to effectively limit the flow of ionized gases from the center pole to the outer poles during high current interruption.

These objects as well as other objects of this invention will become readily apparent after reading the following description of the accompanying drawings in which:

FIG. 1 is a plan view ofa circuit breaker constructed in accordance with teachings of the instant invention.

FIG. 2 is a longitudinal cross-section taken through line 2-2 of FIG. 1, looking in the direction of arrows 2-2 and including a handle operating mechanism, not shown in FIG. 1.

FIG. 3 is an exploded perspective of one overcenter toggle mechanism and selected elements connected thereto.

FIG. 4 is an exploded perspective of the movable contact structure for one pole.

FIG. 5 is a side elevation of the spring supporting operating member of the contact'operating mechanism.

FIGS. 6 and 7 are plan and side elevations respectively of the operating member of FIG. 5, looking in the directions of the respective arrrows 6-6 and 7-7 of FIG. 5.

FIG. 8 is a side elevation of the contact operating mechanism for one pole with the near side of the frame removed. 1

FIG. 9 is an end view of one side of the mechanism frame showing mounting of a positive ON indicator lever and the position of the latter relative to elements of the mechanism that cooperate with this lever.

FIG. 10 is a cross-section taken through line 10-10 of FIG. 11, looking in the direction of arrows 10-10 and illustrating the operating member of the center pole connected to the circuit breaker handle means.

FIG. 11 is an end view of the elements of FIG. 10 looking in the direction of arrows 11-11 of FIG. 10.

FIG. 12 is a plan view of the circuit breaker handle.

FIGS. 13 and 14 are side and end views, respectively, of the handle, looking in the directions of the respective arrows 13-13 and 14-14 of FIG. 12.

FIGS. 15, 16 and 17 are cross-sections taken through the respective lines -15, 16-16, and 17-17 of FIG. 10, looking in the directions of the respective arrows 15-15, 16-16, and 17-17.

FIG. 18 is a fragmentary cross-section taken through line 18-18 of FIG. 14, looking in the direction of arrows 18-18.

Now referring to the figures. Three phase molded case circuit breaker of FIGS. 1 and 2 includes an individual overcenter spring-powered toggle operating mechanism. Prior art examples of circuit breakers having more than a single operating mechanism for all phases are disclosed in U. S. Pat. Nos. 2,067,935 and 3 1 25 ,65 3.

Circuit breaker 25 includes a molded housing constructed of base 26 and removable cover 27 joined along line 28, and provided with longitudinal internal partitions 31, 32 which divide housing 26, 27 into three longitudinally extending compartments, one for each phase of circuit breaker 25. Cover 27 is provided with aperture 29 through which stubby bifurcated extension 33 of operating handle means 30 extendsEach section ofhandle extension 33 receives an individual pin 34 extending upwardly from the web portion of inverted generally 'U -shaped operating yoke member 35 of the center phase. Operating members 35 of the outer phases are each secured to handle means 30 by a pair of screws 152.

Member 35 is pivoted to the spaced arms of generally U-shaped operating mechanism frame 36 at outwardly extending lugs 37. Bolts 48, received by threaded apertures of inturned edges 36a at the bottom of frame 36, fixedly secure the latter to base 26. Transverse tie member 49 is riveted to the arms of frame 36 to maintain spacing therebetween and to stabilize the frame structure.

Four-tensioned coil springs 38, each connected at one end thereof to the web of operating member 35, combine to constitute the main operating spring means for the overcenter toggle-type contact operating mechanism. The other ends of springs 38 are connected to spaced plates 39, 39 that are pivotally mounted to toggle knee pin 41 connecting upper 42 and lower 43 toggle links; The upper ends of upper toggle links 42 are pivotally connected to the spaced arms of latchable cradle at pins 44, and the lower ends of lower toggle links 43 are pivotally connected to contact carrier 45 by rod 46 that extends between the spaced arms of contact carrier 45. The spaced arms of cradle 40 are positioned adjacent the inner surfaces of the spaced arms of frame 36 and are pivotally connected thereto by pins 47 that are secured to frame 36.

Under normal operating conditions plate 51, secured to web 40a of cradle 40, is in engagement with forward latching surface 52 of auxiliary latch 53. The latter is loosely mounted to pivot rod 55 extending between the spaced'arm of mechanism frame 36 and slightly outboard thereof. The coiled end sections of torsion spring member 56 are'wound about pivot rod 55, with the ends of these sections bearing against rod 57 and auxiliary latch 53 to bias the latter counterclockwise against stop rod 58. The ends of rods 57 and 58 are supported by the arms of frame 36. Leaf spring 73 secured to auxiliary latch 53 bears against pivot rod 55 biasing latch 53, so that rod 55 will normally lie at the central portion of V-shaped notch 74 of primary latch 53.

The ends of rod 55 projecting outboard of mechanism frame 36 are engaged by the hooked portions at the forward extension 59 of the arms for U-shaped trip unit frame 60, whose web portion is seated on a forward surface of load strap 61, being secured thereto by bolts 62 that extend through clearance apertures in strap 61 and are received by threaded inserts molded in base 26.

Rear latch tip 54 engages latch tip 63 at the U-shaped forward arm of primary latch 65, whose rear latch tip 64 is engaged by latch plate 67 mounted on one leg of L-shaped carrier 66. Primary latch 65 is pivotally mounted to trip unit frame 60 at stub shaft 69, and the carrier is pivoted on rod 68 to frame 60. Tension spring biases primary latch 65 in a clockwise direction about pivot 69. The other leg of carrier 66 is provided with transversely extending pin 71 that projects into triangular window 72 of primary latch 65 at a portion thereof near rear latch tip 64, for a reason to be hereinafter explained. Tension spring 76, connected between frame 60 and carrier extension 66a, biases carrier 66 in a counterclockwise direction about its pivot 68 toward latching position. i

When automatic tripping occurs, carrier 66 in the faulted phase is moved clockwise either by the deflection of bimetal 77 or movement of magnetic armature 78, causing latch plate 67 to release primary latch 65, which in turn releases secondary latch 53 and permits main operating springs 38 to rotate cradle 40in a counterclockwise direction to break toggle 42, 43. The force from main spring 38 acts through cradle 40, primary latch 53, and secondary latch 65 to drive cam surface 78a, bounding opening 72, against extension 71 to rotate carrier 66 clockwise, with surface 79 thereof engaging ear 81 of extension 82 on tripper bar which extends between all three phases. This causes tripper bar 80 to rotate in a counterclockwise direction, so that extensions 82 in the non-faulted phases rotate counterclockwise with cam surfaces 83 thereof engaging transversely extending pin 84 of carriers 66 in the nonfaulted phases, rotating them clockwise or in the tripping direction, to release the cradle latching systems in the non-faulted phases, so that the contacts of all three phases are open.

In order to prevent closing of the contacts of anyone phase before the operating mechanisms of all phases are latched, circuit breaker 25 is provided with a defeater latching system including defeater latch 80 and defeater lever 90. Latch 80'is pivotally mounted upon rod 55 and includes protrusion 81extending over the rear of cradle 40 when the latter is in latched position. Latch 80' further includes protrusion 82'extending over the forward end of defeater lever in slot 91 thereof. Coiled tension spring 83 is connected between stop rod 57 and latch 80, passing partially around rod 55, to bias latch 80' in a counterclockwise direction about its pivot 55 and maintaining this pivot During normal relatching of circuit breaker 25, inwardly protruding portions of the operating member 35 arms engage outboard portions of pin 44 to pivot cradle 40 clockwise, whereby the latter cams defeater latch 80' away and moves below auxiliary latch 53. Upon release of the circuit breaker operating handle 30, the elements of the latch train 53, 65, 66 move into place. However, should any of these elements fail to properly engage or should cradle 40 not have been moved far enough to engage auxiliary latch 53, cradle 40 will pick up defeater latch protrusion 81, causing clockwise rotation of defeater latch 80'. In turn, this causes defeater latch protrusion 82' to engage defeater lever 90 and rotate the latter counterclockwise, with the rear end 89 thereof contacting carrier extension 71 so that latch plate carrier 66 is pivoted in a clockwise or latch train releasing direction. During this releasing movement of carrier 66, surface 79 thereof engages nose 81 of one trip bar extension 82 to rotate common tripper bar 80 in a counterclockwise direction, with the other extensions 82 on bar 80 engaging pins 84 on the latch plate carriers 66 of the other poles, thereby causing the latch systems of all other poles to be released.

The lower end of bimetal 77 is fixedly secured to shading coil 99, and these elements are fixedly secured to molded frame member 95 secured to trip unit frame 60. The horizontal leg of inverted U-shaped stationary magnetic frame member 98 passes through the center of coil 99. Member 98 is secured to the rear of frame 60, with the vertical legs of member 98 being on opposite sides of load strap 61. The other U-shaped magnetic frame member 96 is secured directly to load strap 61, with the ends of the arms for frame members 96 and 98 confronting one another in spaced relationship. Thus, current flowing in load strap 61 generates flux in magnetic frame 96, 98 which induces current flow in shading coil 99 and thereby generates heat that is conducted to bimetal 77 for heating thereof. Coiled tension spring 97, connected between armature 78 and an element mounted to the rear transverse part 60a of frame 60, biases the former away from two spaced legs 98a extending upward from the horizontal leg of member 98, and is drawn downward toward legs 98a when overload currents generate sufficient magnetic flux in magnetic frame 78, 96, 98.

Withparticular reference to FIG. 4, it is seen that the movable contact structure for each phase of circuit breaker 25 includes eight main contacts 103-110 and a single arcing contact 101. The latter contact 101 is mounted at the forward end of arm 112, which is pivotally mounted to carrier 45 at toggle connecting rod 46. Main contacts 103-110 are arranged in two parallel rows positioned to the rear or arcing contact 101 and disposed at right angles to the plane of movement of arcing contact arm 112.

Main contacts 103-106 in the forward row are mounted to individual contact arms 113-116 respectively, all pivotally mounted to carrier 45 on rod 46. Main contacts 107-110 in the rear row are mounted to the forward end of the respective contact arms 117-120, respectively, pivotally mounted to carrier 45 on rod 102. All of the contact arms 112-120 are connected to load strap 61 by means of individual stacks 121 of flexible sheet conductors. Contact arms 113-116 are in alignment with and extend over the respective contact arms 117-120, so that the latter group of arms 117-120 block downward movement of the former group of arms 113-116 to establish the open circuit position of contacts 103-106 in a manner which will hereinafter be seen. The open circuit position for arcing contact arm 112 is established through engagement thereof with aligned pins 123, 124 which mount the respective pairs of main contacts 117, 1 18 and 119, 120 to auxiliary carriers 125, 126 respectively. Notch 122 along the lower edge of arcing contact arm 112 provides clearance for pins 123, 124.

Auxiliary carrier is an inverted U-shaped member whose arms extend downwardly through cutouts 131, 132 in the web portion of contact carrier 45 and straddle four contact arms 1 13, 114, 117, 1 18. Pin 123 secures contacts 117, 118 to the lower ends of the arms comprising auxiliary carrier 125. The web of auxiliary carrier 125 is biased towards the web of contact carrier 45 by coiled compression spring 127, which is wound around the threaded body of bolt 128 whose head is positioned below the web portions of contact carrier 45. Self-locking nut 133 mounted to bolt 128 is rotated to adjust the loading of spring 127, with the rectangular shoulder of bolt 128 cooperating with rectangular cutout 134 in carrier 45 to prevent rotation'of bolt 128. Thus, in the open circuit position, spring 127 biases the web of auxiliary contact carrier 125 against the web of contact carrier 45, and when the contacts are closed there is a space between the webs of these contact carriers 45, 125, so that the force exerted by spring 127 acts to bias contacts 107, 108 into firm electrical engagement with their respective cooperating contact portions on line strap 136.

The mounting of contact arms 119, 120 to auxiliary contact carrier 126 and mounting of the latter to contact carrier 45 is the same as the mounting of contact arms 117, 118 and auxiliary carrier 125, so that this description will not be repeated.

Biasing forces for each of the contacts 103-106 in the forward row are provided by individual coiled compression springs 138, and each of these springs is mounted in the same way so that only the mounting of one of these springs will be described. The lower end of spring 138 extends into depression 139 in the upper surface of main contact arm 1 13, and the rear of spring 138 extends into tubular support 141 through the open bottom thereof. Support 141 is mounted to the upper surface of carrier 45 at the web portion thereof, and its upper end is threaded to receive adjusting screw 142 whose lower end bears against disc 143 abutting the upper end of spring 138. If screw 142 is adjusted to set the contact pressure exerted by spring 138, lock nut 144 is tightened to lock this adjustment.

In order to increase the area of engagement between main contacts 103-110 and their respective cooperating stationary main contacts in the very limited space available, it is noted that each of the main contacts is provided with a portion extend-ing outward of its respective contact arm. That is, in order to utilize the space below arcing contact 112, main contacts 104, 105, 108, 109 have been extended beyond their respective contact arms 114, 115, 118, 119 to project below arcing contact arm 112. Similarly, main contacts 103, 106, 107, 110 have been extended outboard from their respective contact arms 113, 116, 117, 120, to lie in the space below the outboard arms of auxiliary contact carrier 125, 126 and other elements used to connect the movable contact structure to the contact operating mechanism.

The forward end of arching contact arm 1 12 is biased downward away from the web portion of contact carrier 45 by coiled compression spring 171 whose lower end is positioned by pin 172 extending upward from arm 112. The upper end of spring 171 extends into tuand abuts the closed upper end thereof.

The spaced arms of contact carrier 45 are provided with rearward extensions 45a, 45b that are spaced by and secured to shouldered cylindrical tube 146. After all contact structures, operating mechanisms, latching devices, andautomatic trip units are mounted to base 26, and all adjustments to these mechanisms have been made, the contact structures of all phases are operated to the closed circuit position, so that the tubular members 146 of all phases are axially aligned and are positioned above barriers 31, 32 and the longitudinal sides of base 26. Thereafter, cylindrical tie bar 147 is driven longitudinally in the members 146 of all phases to constitute a rigid mechanical connection between the movable contact structures of all phases. The fit between tie rod 147 and tubular members 146 is tight enough to prevent unintentional axial movement of tie rod 147, yet permits tie rod 147 to be removed for convenient servicing and replacement of parts. Mechanism frame 36 is provided with aligned elongated slots 148 to provide clearances for movement of rod 147 during opening and closing of the movable contact structures.

The construction of operating member 35 is best seen by reference to FIGS. -7. In particular, inverted U-shaped operating member 35 includes spaced arms 201, 202 connected at their upper ends by web 203. Each arm is provided with an inwardly extending cradle engaging resetting protrusion 204, and an elongated slot 205 which receives outwardly extending pin 21 l at the upper end of an individual S-shaped lever 210 which, as will hereinafter be described, functions as the key element of a positive ON indicating means. Web 203 is provided with four pairs of apertures 213, 214 through which the upper ends of springs 38 are hooked. Threaded apertures 215 in web 203 receive the threaded ends of shoulder pins 34 (FIG. in the case of the center pole mechanism, and for the outer poles threaded apertures 215 receive fastening bolts 152.

The lower or free end of each arm 201, 202 is provided with a pair of arcuate bearing notches 238, 239. During assembly of the contact operating mechanism, frame supported bearing studs 37 are received by bearing notches 238, and in this position of operating member 35 springs 38 are substantially relaxed, thereby permitting the mechanism elements to be moved readily to positions where they may be assembled conveniently. After the mechanism elements are assembled, operating member 35 is moved to a new position wherein bearing sutds 37 are received by arcuate notches 239. This repositioning of operating member 35 fully loads springs 38 for contactoperation and contact pressure. This increase in spring pressure results from the fact that the distance between web 203 and operating bearing notch 239 is greater than the distance between assembly bearing notch 238 and spring supporting web 203, so that the repositioning of operating member 35 moves the upper ends of main spring sections 38 away from the lower ends thereof which are secured to members 39 pivotally mounted on toggle knee.

Each S-shaped lever 210 is pivotally mounted to a pin 209 extending outward from the side of mechanism frame 36 (see FIGS. 8 and 9). At a point between pivot 209 and pin 211, lever 210 is provided with pin means 212 extending inwardly through a clearance aperture 191 in frame 36 to cooperate with lower toggle link 43 andprevent operating member 35, and handle 30 secured thereto, from moving to a contact open position unless the contacts are actually open.

More particularly, when handle 30 is moved in a clockwise direction with respect to FIG. 8 to open circuit breaker 25, acting through pin 211 in slot 205 operating member 35 moves lever 210 clockwise about pivot 209. This moves pin 212 on lever 210 toward knee 41 of toggle 42, 43. However, unless toggle 42, 43 collapses, and this may only occur when contact carrier 45 moves to open circuit position, lower toggle link 43 blocks movement of pin 212 so that pin 211 prevents handle 30 from pivoting clockwise to open circuit position; In the event there is aminor malfunction of the contact operating mechanism causing carrier 45 to stick in contact closed position, the engagement of pin 212 with link 43 may collapse toggle 42, 43 to bring about contact opening.

As best seen in FIGS. 12-18, handle 30 includes transverse bar portion 217 of generally rectangular cross-section provided with counterbored apertures 218 through which bolts 152 extend. Each section of bifurcated, stubby extension33 at the central region of handle 30 is provided with a cylindrical recess 219, extending inward from the bottom thereof and stopping just short of transverse apertures 221 in the arms of extension 33. Apertures 221 receive the ends of roll pin 233 rotatably supporting force transmitting roller 222. Friction reducing washers 223 are disposed at each end of roller 222. lntegrally formed arcuate shield 226 at the center of handle 30 is provided to close cover aperture 29 regardless of the position of handle 30. The lower surface of bar 217 is provided with recesses 227 to receive the upper ends of main spring sections 38.

Extending downward from the sides of arcuate shield 226 are insulating sheet barriers 231, 232, each secured to handle 30 by a pair of screws 230. Notches 234 extending upward from the lower end of each barrier 231, 232 provide clearance spaces through which transverse movable contact tie bar 147 extends. Insulating discs 235, 236 are floatingly mounted on tiebar 147, with disc 235 being interposed between barrier 231 and operating member arm 201, and disc 236 being interposed between barrier 232 and operating member arm 202.

During interruption of high currents, the pressure within the center pole is greater than the pressures in the outer poles, so that ionized gases tend to flow from the center pole to the outer pole. If this gas flow is permitted, phase-to-phase arcing will result. However, the greater pressure in the center pole forces discs 235, 236 to seat firmly against insulating barriers 231, 232, secured to handle 30, thereby closing clearance slots 234 therein. In addition, this excess pressure forces barriers 231, 232' against housing partitions 31, 32 to substantially close off potential paths for escape of ionized gases directly from the center phase to the outer phases.

For those features of construction in circuit breaker 25 that have not been described in detail herein, reference is made to one or more of the copending applica- 9 tions Ser. Nos. 275,568; 275,577; 275,446; 275,507; 275,454; 275,508; 275,621; 275,623; 275,624;

275,569; 275,552; 275,521; 275,523; and 275,622, all filed of even date herewith, and all assigned to the assignee of the instant invention.

Although there has been described a preferredembodiment of this novel invention, many variations and modifications will now become apparent to those skilled in the art. Therefore, this invention is to be limited not by the specific disclosure herein but only by the appending claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

l. A circuit breaker including a housing formed by a base and a cover; said housing having longitudinally extending internal barriers dividing said housing into sideby-side compartments; an individual cooperating contact means including a movable contact structure in each of said compartments; operating means connected to said movable contact structures for opening and closing said cooperating contact means; said operating means including a plurality of spring powered mechanisms, each disposed in a different one of said compartments; each of said spring powered mechanisms including an operating member; handle means including a transverse bar disposed within said housing and connected directly to each of said operating members for operating the latter in unison; said handle means including a stubby extension projecting from said bar at its mid-region through an aperture in said cover; metal pin means at said mid-region extending into said handle means and connecting a first of said operating members to said bar; and fastening means rigidly connecting a second and third of said operating members to said bar on opposite sides of said midregion whereby all three of said operating members simultaneously move to-and occupy corresponding positions.

2. A circuit breaker as set forth in Claim 1 in which the extension of the handle means includes spaced arms; said pin means including an individual pin extending into each of said arms; transmitting means disposed between said arms to transmit operating forces to said handle means; additional fastening means in close proximity to said metal pin means connecting said transmitting means to said arms.

3. A circuit breaker as set forth in Claim 2 in which the additional fastening means extends generally at right angles to said pin means and parallel to the longitudinal axis of said bar.

4. A circuit breaker as set forth in Claim 3 in which the transmitting means comprises a roller mounted to rotate freely about an axis defined by the additional fastening means.

5. A circuit breaker as set forth in Claim 1 in which there is a transverse tie bar interconnecting said plurality of spring powered mechanisms; said handle means also including first and second generally parallel spaced insulating sheet barriers projecting laterally from said bar on opposite sides of said first operating member; said barriers having clearance slots through which said tie bar extends and within which said tie bar is movable transverse to the planes of said barriers.

6. A circuit breaker as set forth in Claim 5 also including first and second additional insulating sheet barriers disposed inboard of and adjacent to the respective first and second barrier; said additional barriers being mounted to said tie bar and being movable therewith.

7. A circuit breaker as set forth in claim 6 in which the clearance slots extend inward from the edges of said barriers most remote from said bar; said edges being adjacent to and inboard of the internal barriers bounding the compartment wherein the first operating member is disposed.

8. A circuit breaker as set forth in Claim 1 in which the bar is generally of rectangular cross-section and said fastening means extends generally parallel to the minor axis of the rectangular cross-section.

9. A circuit breaker as set forth in claim 1 in which the operating members are of identical construction, with each having first and second threaded apertures; said fastening means com-prising screws received by each of the threaded apertures of the second and third operating members; said pin means comprising first and second pins whose first ends extend into smoothwalled recesses of said bar and whose other ends are threaded and are received by the threaded apertures of the first operating member.

10. A circuit breaker as set forth in Claim 9 in which the stubby lateral extension is bifurcated with each section thereof having a continuation of the smoothwalled recesses of the bar; said screws extending through clearance apertures in the bar extending transverse to the longitudinal axis thereof; said smoothwalled recesses and said threaded apertures being parallel to each other and being spaced along the longitudinal axis of the bar;

11. A circuit breaker as set forth in claim 5 also including floating insulating sheet barriers mounted on said tie bar in position to be engaged with said barriers of said handle means during current interruption to cover said clearance slots.

12. A circuit breaker as set forth in claim 1 l in which the floating barriers are interposed between the barriers of said handle means and the sides of said first operating member. 

1. A circuit breaker including a housing formed by a base and a cover; said housing having longitudinally extending internal barriers dividing said housing into side-by-side compartments; an individual cooperating contact means including a movable contact structure in each of said compartments; operating means connected to said movable contact structures for opening and closing said cooperating contact means; said operating means including a plurality of spring powered mechanisms, each disposed in a different one of said compartments; each of said spring powered mechanisms including an operating member; handle means including a transverse bar disposed within said housing and connected directly to each of said operating members for operating the latter in unison; said handle means including a stubby extension projecting from said bar at its mid-region through an aperture in said cover; metal pin means at said mid-region extending into said handle means and connecting a first of said operating members to said bar; and fastening means rigidly connecting a second and third of said operating members to said bar on opposite sides of said mid-region whereby all three of said operating members simultaneously move to and occupy corresponding positions.
 2. A circuit breaker as set forth in Claim 1 in which the extension of the handle means includes spaced arms; said pin means including an individual pin extending into each of said arms; transmitting means disposed between said arms to transmit operating forces to said handle means; additional fastening means in close proximity to said metal pin means connecting said transmitting means to said arms.
 3. A circuit breaker as set forth in Claim 2 in which the additional fastening means extends generally at right angles to said pin means and parallel to the longitudinal axis of said bar.
 4. A circuit breaker as set forth in Claim 3 in which the transmitting means comprises a roller mounted to rotate freely about an axis defined by the additional fastening means.
 5. A circuit breaker as set forth in Claim 1 in which there is a transverse tie bar interconnecting said plurality of spring powered mechanisms; said handle means also including first and second generally parallel spaced insulating sheet barriers projecting laterally from said bar on opposite sides of said first operating member; said barriers having clearance slots through which said tie bar extends and within which said tie bar is movable transverse to the planes of said barriers.
 6. A circuit breaker as set forth in Claim 5 also including first and second additional insulating sheet barriers disposed inboard of and adjacent to the respective first and second barrier; said additional barriers being mounted to said tie bar and being movable therewith.
 7. A circuit breaker as set forth in claim 6 in which the clearance slots extend inward from the edges of said barriers most remote from said bar; said edges being adjacent to and inboard of the internal barriers bounding the compartment wherein the first operating member is disposed.
 8. A circuit breaker as set forth in Claim 1 in which the bar is generally of rectangular cross-section and said fastening means extends generally parallel to the minor axis of the rectangular cross-section.
 9. A circuit breaker as set forth in claim 1 in which the operating members are of identical construction, with each having first and second threaded apertures; said fastening means comprising screws received by each of the threaded apertures of the second and third operating members; said pin means comprising first and second pins whose first ends extend into smooth-walled recesses of said bar and whose other ends are threaded and are received by the threaded apertures of the first operating member.
 10. A circuit breaker as set forth in Claim 9 in which the stubby lateral extension is bifurcated with each section thereof having a continuation of the smooth-walled recesses of the bar; said screws extending through clearance apertures in the bar extending transverse to the longitudinal axis thereof; said smooth-walled recesses and said threaded apertures being parallel to each other and being spaced along the longitudinal axis of the bar.
 11. A circuit breaker as set forth in claim 5 also including floating insulating sheet barriers mounted on said tie bar in position to be engaged with said barriers of said handle means during current interruption to cover said clearance slots.
 12. A circuit breaker as set forth in claim 11 in which the floating barriers are interposed between the barriers of said handle means and the sides of said first operating member. 